Electrocardiographic manifestations: acute myopericarditis.

Acute, or so-called "dry," myopericarditis occurs in the presence of diffuse inflammation of the pericardial sac and superficial epicardium from a multitude of infectious and inflammatory processes. This inflammation results in a current of myocardial injury resulting from the epicardial irritation manifested by a number of electrocardiographic findings. Classically, the electrocardiographic changes have been described as an evolution through several distinct stages involving ST segment elevation with PR segment depression, normalization of the ST segment abnormality with T wave inversion, and eventual normalization of the electrocardiogram over a period of days to several weeks. The following discussion focuses on the electrocardiographic manifestations of acute myopericarditis and includes findings useful in establishing the diagnosis as well as distinguishing the disease from other syndromes, particularly acute myocardial infarction.